The present invention relates to a lithium secondary cell (hereinafter simply referred to as “cell”), and more particularly, to a lithium secondary cell with excellent productivity and space-saving capabilities.
The development of lithium secondary cells is underway as motor drive power supplies for electric cars and hybrid electric cars (hereinafter simply referred to, as “electric car, etc.”) in response to a growing international demand for resource and energy savings to protect the global environment.
This lithium secondary cell contains an inner electrode body (hereinafter simply referred to as “electrode body”) made up of a positive electrode and a negative electrode wound or laminated together with a separator made of a porous polymer film inserted in between so that the positive electrode and the negative electrode do not directly contact each other.
As shown in FIG. 20, a conventional wind type inner electrode body 61 is manufactured with a positive electrode 62 and negative electrode 63 wound with a separator 64 inserted in between, each provided with at least one collector tab 65 for the positive electrode and one collector tab 66 for the negative electrode (hereinafter referred to as “collector tabs 65 and 66”). Then, as shown in FIG. 19, the edges on the opposite side of the collector tabs 65 and 66 connected to the electrode plates 62 and 63 are attached to internal terminals 69A and 69B, etc. Reference numeral 76 denotes an elastic body (packing); 77, an insulation polymer film; 78, a pressure reducing valve; 79, a metallic foil.
Metallic foils, etc. are used for the electrode plates, such as aluminum, etc. for the positive electrode and copper or nickel for the negative electrode as collector substrates, and each electrode plate is formed by applying an electrode active material and the collector tabs are placed on at least one side of these collector substrates.
However, the collector tabs need to be attached to the electrode plates one by one, for example, by spot-welding, when the electrode body is wound, and the problem is that its process is complicated. Furthermore, at the edges on the opposite side connected to the electrode plates of the collector tabs, the plurality of collector tabs need to be bound and attached to the internal terminals by, for example, riveting, and therefore this process is also complicated and has a problem that it is not easy to connect the collector tabs while maintaining them at low resistance. Furthermore, there is another problem that connecting the electrode body and internal terminals using a plurality of collector tabs requires quite a large space.